“Form a sea star shape,” directs a computer scientist, sending the command to 1,024 little bots simultaneously via an infrared light. The robots begin to blink at one another and then gradually arrange themselves into a five-pointed star. “Now form the letter K.”

The ‘K’ stands for Kilobots, the name given to these extremely simple robots, each just a few centimeters across, standing on three pin-like legs. Instead of one highly-complex robot, a “kilo” of robots collaborate, providing a simple platform for the enactment of complex behaviors.

Just as trillions of individual cells can assemble into an intelligent organism, or a thousand starlings can form a great flowing murmuration across the sky, the Kilobots demonstrate how complexity can arise from very simple behaviors performed en masse (see video). To computer scientists, they also represent a significant milestone in the development of collective artificial intelligence (AI).

Given a two-dimensional image, the Kilobots follow simple rules to form the same shape. Visually, the effect is similar to a flock of birds wheeling across the sky. “At some level you no longer even see the individuals; you just see the collective as an entity to itself,” says Radhika Nagpal. (Image courtesy of Mike Rubenstein and Science/AAAS.)

“The beauty of biological systems is that they are elegantly simple—and yet, in large numbers, accomplish the seemingly impossible,” says Nagpal. “At some level you no longer even see the individuals; you just see the collective as an entity to itself.”

“Biological collectives involve enormous numbers of cooperating entities—whether you think of cells or insects or animals—that together accomplish a single task that is a magnitude beyond the scale of any individual,” says lead author Michael Rubenstein, a research associate at Harvard SEAS and the Wyss Institute.